The objective of this proposal is to assess whether the quantity and drug susceptibility of HIV in cervicovaginal secretions correlate with those in plasma among HIV-infected women receiving antiretroviral therapy. The study has important implications for both heterosexual and vertical transmission of HIV. The study will enroll four separate groups of HIV-infected women and follow them prospectively for 36 months. Group A will include 40 women who are antiretroviral naive and who will begin therapy with combination nucleoside reverse transcriptase inhibitor (RTI) therapy. Group B will include 40 women who are already on combination nucleoside RTI, and who will begin a protease inhibitor. Group C will include 20 women who are antiretroviral naive who do not wish to begin therapy. Group D will include 20 recent seroconverters (within one year). HIV load will be measured in plasma and cervicovaginal secretions by NASBA. HIV resistance phenotype will be determined by combined approaches of isolate phenotyping and genotyping of proviral DNA predominately in viral isolates.